Groundwater potential recharge areas delineation using groundwater potential recharge index (GPRI) within arid areas: Ghomrassen, south Tunisia

Abstract

The Ghomrassen region is located in southern Tunisia, which is an arid area where the annual rainfall does not exceed 150 mm. This region suffers from water table drawdown and scarcity of surface water. Groundwater is of strategic importance to meet the population and economic needs. Groundwater recharge estimation and fundamental controlling factors assessment were utmost importance solutions for sustainable groundwater management and groundwater protect. This study aims to assess the main factors controlling groundwater recharge and delineate potential recharge area of Ghomrassen aquifer. To achieve this objective, a groundwater potential recharge index (GPRI) was computed using five parameters such as soil lithology, land use/cover, lineament density, slope, and drainage density. For each parameter a score and weight were assigned and thematic maps were developed. The results indicate that about 35% of the study area is designated as excellent potential recharge, whereas 18% of study shows a moderate recharge and lower potential recharge covers 47% of study area. A potential groundwater recharge of Ghomrassen aquifer was estimated is about 5.4 Mm3.y−1. The results show that the most favorable areas for recharging are the upstream part formed by fractured and fissured rocks and the central part of the Ghomrassen basin formed by recent alluvium. The presented GPRI methodology can be helpful for the planning of various water projects locations of artificial recharge structures and wells establishment.